database design

[Jean-Yves LEBLEU <jl...@gmail.com>]

Hi all,

Just some thoughts and question I have about cassandra data modeling.

If I understand well, cassandra is better on writing than on reading.
So you have to think about your queries to design cassandra schema. We
are doing incremental design, and already have our system in
production and we have to develop new queries.
How do you usualy do when you have new queries, do you write a
specific job to update data in the database to match the new query you
are writing ?

Thanks for your help.

Jean-Yves

Re: database design

[Victor Kabdebon <vi...@gmail.com>]

Dear Jean-Yves,

You can have a different approach of the problem.
You need on one side a relational database (MySQL, PostGreSQL) or SolR (as
an very efficient index) and on the other side Cassandra. The relational
database or SolR must contain the minimum amount of information possible : a
date and only the relevant data. It enabled me to keep a simple model for
Cassandra.
Cassandra will act as a "vault" where you keep all the data and then you
dispatch the data from Cassandra to the relational database or SolR. When
you want to query you query against SolR or the relational data the key /
column / supercolumn and you retrieve the complete data from Cassandra. The
hard thing is to maintain the coherence between the query part and the
Cassandra part.
I speak from personal experience but it was very hard for me to use only
Cassandra to do everything my (small amateur) website needed. Now I found an
alternative I use : Cassandra (data vault) + Redis (Sessions and other
volatile data) + SolR (Search engine) + PostGreSQL ( for relational
queries).

Best regards,
Victor Kabdebon
http://www.voxnucleus.fr

2011/4/13 Edward Capriolo <ed...@gmail.com>

> On Wed, Apr 13, 2011 at 10:39 AM, Jean-Yves LEBLEU <jl...@gmail.com>
> wrote:
> > Hi all,
> >
> > Just some thoughts and question I have about cassandra data modeling.
> >
> > If I understand well, cassandra is better on writing than on reading.
> > So you have to think about your queries to design cassandra schema. We
> > are doing incremental design, and already have our system in
> > production and we have to develop new queries.
> > How do you usualy do when you have new queries, do you write a
> > specific job to update data in the database to match the new query you
> > are writing ?
> >
> > Thanks for your help.
> >
> > Jean-Yves
> >
>
> Good point, Generally you will need to write some type of range
> scanning/map reduce application to process and back fill your data.
>

Re: database design

[aaron morton <aa...@thelastpickle.com>]

In some cases you may be able to add a secondary index. 

Aaron

On 14 Apr 2011, at 03:11, Edward Capriolo wrote:

> On Wed, Apr 13, 2011 at 10:39 AM, Jean-Yves LEBLEU <jl...@gmail.com> wrote:
>> Hi all,
>> 
>> Just some thoughts and question I have about cassandra data modeling.
>> 
>> If I understand well, cassandra is better on writing than on reading.
>> So you have to think about your queries to design cassandra schema. We
>> are doing incremental design, and already have our system in
>> production and we have to develop new queries.
>> How do you usualy do when you have new queries, do you write a
>> specific job to update data in the database to match the new query you
>> are writing ?
>> 
>> Thanks for your help.
>> 
>> Jean-Yves
>> 
> 
> Good point, Generally you will need to write some type of range
> scanning/map reduce application to process and back fill your data.

Re: database design

[Edward Capriolo <ed...@gmail.com>]

On Wed, Apr 13, 2011 at 10:39 AM, Jean-Yves LEBLEU <jl...@gmail.com> wrote:
> Hi all,
>
> Just some thoughts and question I have about cassandra data modeling.
>
> If I understand well, cassandra is better on writing than on reading.
> So you have to think about your queries to design cassandra schema. We
> are doing incremental design, and already have our system in
> production and we have to develop new queries.
> How do you usualy do when you have new queries, do you write a
> specific job to update data in the database to match the new query you
> are writing ?
>
> Thanks for your help.
>
> Jean-Yves
>

Good point, Generally you will need to write some type of range
scanning/map reduce application to process and back fill your data.